Prolog - Term replacement, Term alteration in workflow graphs

In this link ( Meta Interpreter ) I believe to have found a nifty way of solving a problem I have to tackle, but since my prolog is very bad I'd first ask if its even possible what I have in mind.

I want to transform certain parts of a workflow/graph depending on a set of rules. A graph basically consists of sequences (a->b) and split/joins, which are either parallel or conditional, i.e. two steps run in parallel in the workflow or a single branch is picked depending on a condition (the condition itself does not matter on this level) (parallel-split - (a && b) - parallel-join) etc. Now a graph usually has nodes and edges, with the form of using terms I want to get rid of edges.

Furthermore each node has a partner attribute, specifying who will execute it.

I'll try to give a simple example what I want to achieve:

A node called A, executed by a partner X, connected with a node called B, executed by a partner Y.

A_X -> B_Y
seq((A,X),(B,Y))

If I detect a pattern like this, i.e. two steps in sequence with different partne开发者_如何转开发rs, I want this to be replaced with:

A_X -> Send_(X-Y) -> Receive_(Y-X) - B_Y // send step from X to Y and a receive step at Y waiting for something from X

seq((A,X), seq(send(X-Y), seq(receive(Y-X), B)))

If anyone could give me some pointers or help to come up with a solution I would be very thankful!

A graph basically consists of sequences (a->b) and split/joins, which are either parallel or conditional, i.e. two steps run in parallel in the workflow or a single branch is picked depending on a condition

This sounds an awful lot like an and/or graph. Prolog algorithms on these graphs are covered by Ivan Bratko in Prolog Programming for Artificial Intelligence, chapter 13. Even if your graphs aren't really and/or graphs, you may be able to adapt some of these algorithms to your task.